Hi guys,

I have a question about AC breaker size. My impression was that the breaker needs to be spec'd for the max sustained output of the inverter. So in my case I have a Goodwe GW3048-EM which has a max ouput (while grid supplied) of 3kW. So if I add 25% I get 3.75kW, divided by 230V is 16.3A. Supposedly you can round down if you are less than half an amp over the nearest standard size. So presumably 16A breakers would be fine.

However I am a bit perplexed by something on the data sheet. It says "Max. Apparent Power from Utility Grid - 5300VA". Now I know there is a bunch of stuff related to power factor and the types of loads you run (though you shouldn't be running heavy inductive loads on this inverter at all) resulting in a difference in your real power vs apparent power. But I just don't know where that number comes from. My thought was that it could be a momentary number for a few milliseconds, or perhaps if you are passing 3kW through from the grid and charging the batteries at 2.4kW? My assumption is that is not possible with this inverter, though I could be wrong.

At any rate, if anyone could help explain this or point me in the right direction I would appreciate it. I'm pretty sure 16A would work but I'm trying to make sure I understand what I am doing, not just making something that should probably work. Yesterday was a rabbit hole of correct grounding practice which led to a very helpful post by Gnome about using 230V coil SPDT relays.

EDIT: Ok so I overlooked something major. The spec sheet says that this thing can pull a max of 23.6A, that's like 5.4kW at 230V! How is that possible with a 3kW inverter? I don't think that is an instantaneous figure either.

Edited November 15, 20223 yr by Jankzilla

That inverter can charge the battery from the grid, while passing power through. So the breaker to the inverter should be specced for 5300VA, and also the wires.

The manual also clears up any confusion:

I can really recommend reading the manual before you install it.

Edited November 16, 20223 yr by P1000

Thanks @P1000,

 

How embarrassing. I assure you I have been reading the manual, but I missed that. Thanks very much. To be fair, my manual is different and the info is a little italic line, not a table. Need to read the fine print!

 

Is there any harm in using 32A breakers if it’s connected to a 20A circuit? I was thinking that might be a bad idea but presumably the 20A DB breaker would protect the cable leading to the inverter if there was a problem? I’m going to try to limit the current in the settings.
 

Just wondering if I ought to spec the inverter’s AC breakers down until I can run thicker cable. My impression is that 3 prong plugs are only 16A so my inclination is to put 16A breakers on the inverter side in the mean time.

JZ

Edited November 16, 20223 yr by Jankzilla